1. Field of the Invention
The present invention is related to a regulator, and particularly to a regulator that can rapidly recover an output voltage and a load current of the regulator when the regulator enters a heavy load mode from a light load mode.
2. Description of the Prior Art
Please refer to FIG. 1A and FIG. 1B. FIG. 1A is a diagram illustrating a regulator 100 according to the prior art, and FIG. 1B is a diagram illustrating a load current Iload, a first driving current I1 and an output voltage Vout of the regulator 100 during operation of the regulator 100 in a heavy load mode and a light load mode. As shown in FIG. 1A, when the regulator 100 enters the light load mode (power saving mode), a first amplifier 102 and a first P-type metal-oxide-semiconductor transistor 104 are turned off, resulting in the first driving current I1 flowing through the first P-type metal-oxide-semiconductor transistor 104 being reduced to zero. Meanwhile, a second amplifier 106 and a second P-type metal-oxide-semiconductor transistor 108 are still turned on, so a second driving current I2 flowing through the second P-type metal-oxide-semiconductor transistor 108 is still supplied to a load 110 and a feedback circuit 112. As shown in FIG. 1B, when the regulator 100 enters the light load mode, the load current Iload is decreased and the first driving current I1 is reduced to zero. However, the output voltage Vout of the regulator 100 is still unchanged due to turning-on of the second amplifier 106 and the second P-type metal-oxide-semiconductor transistor 108.
When the regulator 100 enters the heavy load mode from the light load mode, the first amplifier 102 and the first P-type metal-oxide-semiconductor transistor 104 are turned on again. As shown in FIG. 1B, the load current Iload is increased rapidly, and the first driving current I1 is increased slowly because a voltage drop between a source terminal and a gate terminal of the first P-type metal-oxide-semiconductor transistor 104 is increased more slowly. Meanwhile, because the load current Iload is increased rapidly, and the first driving current I1 is increased slowly, the output voltage Vout of the regulator 100 is decreased until the first driving current I1 is stable. Therefore, the regulator 100 temporarily cannot provide a stable voltage to the load 110 when the regulator 100 enters the heavy load mode from the light load mode.